Conventionally, a substrate mounting an LED is attached to an edge of a radiator, a globe is attached to the edge of the radiator in a manner that the globe covers the substrate, a case for storing a lighting circuit for lighting the LED is attached to the other edge of the radiator, and a cap is provided to the other edge of the case in a self-ballasted lamp using an LED as a light emitting element.
In such a self-ballasted lamp, temperature of the LED is increased by the heat generated by the LED and such an increase in temperature causes a decrease in light emission of the LED, as well as shortened life of the LED. Therefore, it is requested to suppress a rise in temperature of the LED and for that purpose, for example, the radiator is formed of a metallic material having good thermal radiating properties or the like.
Moreover, although this is not a case of a self-ballasted lamp including a globe, there is known an LED lamp in which heat-radiating fins are provided in the periphery of the radiator and a fan is provided inside the radiator so that the heat transmitted from the LED to the radiator is forcibly radiated, as shown in Japanese Laid-Open Patent Publication No. 2007-265892.
However, in the case of a self-ballasted lamp having a globe, radiation efficiency of the LED is poor because the LED is covered with the globe and even if a metallic radiator is used, rise in temperature of the LED cannot be sufficiently suppressed.
Moreover, even if a heat-radiating fin is provided to the radiator of a self-ballasted lamp having a globe and a fan is provided inside the radiator like the case of an LED lamp without a globe so that heat transmitted to the radiator can be forcibly radiated, since the LED is covered with the globe, it is not possible to sufficiently suppress a rise in temperature of the LED.
The present invention has been made in consideration of such a problem and is aimed at providing a self-ballasted lamp which can improve radiation efficiency and suppress a rise in temperature of a light emitting element.